This invention relates to a water-soluble ink and an ink jet recording apparatus using the water-soluble ink. More particularly, it relates to a composition of a water-soluble ink.
Ink used in ink jet recording apparatus such as ink jet printers is made up of components selected from among various materials to have an optimum composition. Dyes, for instance, which can be used include direct dyes, acid dyes, and so forth, which have their several characteristics of choice. Inks comprising direct dyes are characterized by excellent water resistance and light fastness, and inks comprising acid dyes are characterized by high chroma.
With the steadily broadening application of ink jet recording apparatus, an ink composition having a high chroma and excellent water resistance and light fastness has been demanded, but a dye satisfying all these requirements has not yet been found. That is, direct dyes that are excellent in water resistance and light fastness have a low chroma, and acid dyes that provide high chroma have poor resistance to water and light.
An object of the invention is to provide a water-soluble ink composition comprising an optimum combination of a direct dye and an acid dye and having excellent water resistance and light fastness as well as high chroma.
Another object of the invention is to provide an ink jet recording apparatus using the water-soluble ink composition.
The objects of the present invention are accomplished by a water-soluble ink composition comprising (A) a xanthene magenta dye, (B) C.I. Direct Red 227, and (C) at least one of a cyan dye and a yellow dye.
The combination of (A) a xanthene magenta dye, which is an acid dye having satisfactory chroma, and (B) C.I. Direct Red 227, which is a direct dye having satisfactory water resistance and light fastness, provides a water-soluble ink composition having excellent water resistance and light fastness as well as high chroma.
The combination of dyes (A) and (B) is further combined with (C) a cyan dye or a yellow dye to provide a blue or red ink, respectively, or both the cyan dye and the yellow dye as component (C) at appropriate ratios of the dyes to provide a blue or red ink.
In a highly preferred embodiment of the invention, the ink composition has its surface tension adjusted to 40 mN/m or lower by addition of a specific amount of a specific surface active agent.